---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Sun 08/31/03: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:03 AM - Lead Alternative for Valves (lehmansmtl@netzero.com) 2. 04:51 PM - Fuel Pump or Vapor Lock ? (Mike Pierzina) 3. 11:01 PM - Valves and UL GAs (Dean Psiropoulos) ________________________________ Message 1 _____________________________________ Time: 06:03:12 AM PST US Subject: Engines-List: Lead Alternative for Valves From: lehmansmtl@netzero.com --> Engines-List message posted by: lehmansmtl@netzero.com Gentlemen, Until a few years ago, I endeavored to run either 20% 100LL with mogas (or the occasional 100LL fill-up when necessary on trips)to protect against the valve seat to valve face micro-welding (described in a recent posting). For the last few years, I've used a lower cost alternative called AVP (aviation valve protectant) obtained from Canadian Aero Petroleum Products. The same company in the USA is Niagara Airparts. Perhaps Gary can tell us what chemical additive was used decades ago as a lead scavenger in leaded autogas (in North America) because I believe that's what AVP actually is. AVP is described as a vapor phase lubricant, non-toxic and is a added to the aircraft fuel tank in the ratio 1 ml to 10 liters autogas (1:10,000). I've used AVP with both Continental and Lycoming engines but don't have enough experience to prove or disprove its effectiveness (except that to report no valve durability problems, yet). BTW, my HIO-360-D1A had severe valve stem corrosion and considerable valve seat recession after about 500 hours of helicopter service (considered severe). Lead compound deposits are tough on valve stems and guides and, it seems, that lead is only a partial solution even with hardened seats. Mike The best thing to hit the internet in years - NetZero HiSpeed! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month -visit www.netzero.com to sign up today! ________________________________ Message 2 _____________________________________ Time: 04:51:23 PM PST US From: "Mike Pierzina" Subject: Engines-List: Fuel Pump or Vapor Lock ? --> Engines-List message posted by: "Mike Pierzina" Hey Guys, I fired up my 582 the other day and "top end" was rough....I figured it was old fuel....I didn't have a decent hose to sipfon the fuel , so I pulled the fuel line apart and drained most the fuel. I added the new fuel and with a few primes it was running. I warmed it up to 140 degrees and then started to raise the RPM's higher until I could test "top end". It ran great , top end was smooth again. Next day I loaded it on the trailer , packed all the gear, and while I was doing my warm-up I couldn't get it to rev up , I noticed the fuel line going to the rear carb wasn't pushing the fuel. and after the engine would die , I noticed the fuel in the line would return to the fuel pump.... I'm getting a new rebuild kit for the Mikuni fuel pump. Do any of you guys think it has anything to do with "Vapor Lock" .....I wouldn't think so because of the run time the day before 10 - 15 min ...... and wouldn't you know it parts place is closed today... Well, back to work on my Kolb. I'm still fabracating a 2cycle oil tank....which was delayed because of the heat & humidity... Gotta Fly... Mike in MN FSII 503 w/injection "B" w/ 3 blade-66" IVO ,EIS,GPL, 90% done 90% to go... --- Sometimes you just have to take the leap and build your wings on the way down... Gotta Fly... Get advanced SPAM filtering on Webmail or POP Mail ... Get Lycos Mail! ________________________________ Message 3 _____________________________________ Time: 11:01:30 PM PST US From: "Dean Psiropoulos" Subject: Engines-List: Valves and UL GAs --> Engines-List message posted by: "Dean Psiropoulos" A couple other things that have helped auto engines survive Unleaded gas are: Automatic valve rotators and liquid cooling. Automatic valve rotators are something GM began installing on their engines in the late 70s. From what I understand they are a fairly simple mechanism that is installed at the top of the valve stem under the rocker arm. Every time the valve is actuated by the rocker arm the mechanism turns the valve a set number of degrees before it closes. This in effect results in a continuous lapping action of the valve and valve seat. That way when a microscopic piece of the seat welds itself to the valve face, it doesn't continually contact the same spot on the seat and exacerbate the problem. This works really well in my experience, my little 2.8 V6 in my Cheverolet S-10 PU has been run hard for 17 years and 230 thousand miles. After a compression check last year it showed only 1 cylinder down in compression and that was only 10 PSI less than the rest. I attribute part of this longevity to religiously changing my oil and filter EVERY 3000 miles as well. As has been said before, oil changes are cheap insurance. And while oil does not wear out, the additives in it do and when they do they quit holding combustion byproducts in suspension. Then it starts depositing them inside the engine where they turn into a tarry goo that plugs oil galleries and other important engine parts. Also a big difference between airplane and car engines is obviously the cooling systems, car engines run cooler and that's another reason the valves don't erode like VW beatles or airplane engines. The less differential between the melting point of metal and the valve temperature, the faster the metal is going to wear away. Air cooled aircraft engines run almost twice as hot as most car engines and that is a factor in valve problems, that's why the rotax can run UL gasoline and last longer, the heads are liquid cooled (and they use modern engine design techniques, something Lycoming hasn't bothered to do for 50 years). Dean Psiropoulos Tinkerer and RV-6 builder. Don not archive